Telephone-transmitter.



J. G. NOLEN & R. L. McELROY.

TELEPHONE TRANSMITTER.

APPLICATION FILED MAY 4, T914.

JAMES (1 NOLEN, 0F NE'W YORK, BAND EQTBERT 3L, MGELBGY, OF "WEI "X01332, ASSIGrNORS TO MAGNETIC PHQNOGRAEH COIPIPANY, O13 HEM M131 Specification of Letters Patent.

tn, NEW it, it. "122, n.

Patented El i,

Application filexi may -l=, 3.0%. Serial 1*! o. 33%,lo6.

To all whom it 12mg concern:

Be it known that we, JAMES l l cilr'n and ROBERT L. Morn-nor, citizens of the United States of America, and residents of New York, in the county and State of lien York, and W hitestonc, borough of Queens, city and State of New York, r spectiwel have invented lmprovenients in Telephone- .Transrnitters, of which the following is specification.

Our invention relates to improvements in telephone transmitters and the like, and omnprises the combination with the diaphragm and microphone of a telephone transmitter or like instrument. of magnetic means exerting a continual pull on such diaphragm,

j and thereby keeping the diaphragm normolly under tension and also tending to hold that diaphragm normally in a slightly bowed positionythe vibrations of the diaphragm, When-the instrument is in use, taking place on opposite sides of such bowed position. Other. features of our invention will he pointed out hereafter. I

The objects of our invention are, to improvethe clarity, quality and elliciency of telephonic transinissiomto avoid the use of clamping springs in connection With the clin- Bil phragni; to avoid so-celled side noise; and to accom llsh the above ob ects 1) Y sim le compact and relatively iriexpensiveepporetus.

' Figure 3. shows an axia section of 'a tele phone transmitter ern boc ng our invention; Fig.2 shows atrensverse seotion thereof on the line P? of Fig. 1 Fl x 3 shows. an axial section of an alterniitive form of telephone transmitter embodying our invention. Fig. 4' is n'view, more or less diagrammatic, showing means for the mechanical reprocluo plZiOIl ofphonographio sound records in secorclance with our invention; 5

such shown in Figs}, 2 a d. zincl illustinting circuits for the supply of current of thatma 'net froin the main line conductors.

Intelephone transmitters it is con'inion to use a sound-actuated ineinbeiynsnolly e.- dim is a diagrammatic View illustrating the use of'. an electromagnet in o telephone.transmitter. I i

"transmission clue too loose diaphragm.

or rest position oi. the diaphragm is usually of that diaphragm innv he inodilie l by the to some extent reinforce the netninl resili nntnrnl resilience of the tliopl'n 7111 has this creases, so does the lPsL stance of the spring vibrations. ltiloreover, (lio'phragms as com monly employed. in telephone transmitters tend to accentuate tones or high pitch, with reference to tones of low pitch; one result being the familiar strident tone of the. tele phone and another result being it rnuifiing or obscuring of articulate speech ltlltl other sounds.

We have cliscoveretl that magnet or nmgnets may he used. to prevent undue rt-4 sponse to very loud noises by a telephone transmitter with very great advent the use of so-callerl damping spr.' s, and in particular We lief-"efound that o. transmitter cliophragm influenced by n magnet herein (lescribecl, vibrates much more freely than when clamping springs are employed; also that the strident tone 1s eliminated, the un- (loo accentimtion high-pitched tones being avoidmh with the result that the human voice is reproduced at the receiver with pron-- ticslly the natural quality of tone and With much greater clearness in articulation. The

4n egnet maintains the transmitter diaphragm in a. normal slightly howeeil conlition in which the diaphragm is under considerable initial stress; thereby avoiding defects in We have also found that the disturbing side tone to a. large extenteliminated.

In Figs. 1 end We illiistratc a telephone transmitter which. except as to the features embodying our invention, is of Well known type. (it clesignates thensuel month piece. 65 the cliephragjm, 66 the usual bridge, and

67 the usual microphone ccmprising,'as is customary, two carbon disks (38 and 69 between which is a mass of granular carbon 70; carbon disk 69 being carried by a mica diaphragm 71 connected by screw 72 to the telephone diaphragm 65. v we mount an armature 73 of a magnet; which magnet in the construction shown, comprises four horseshoe magnets 7 4: having common pole pieces 75, structurally separate from the magnet Tel but each clamped between two of said magnets. It will be apparent that as voice waves deflect the dia-.

- phragm 65 rearwardly, or to the right of Fig. 1, such deflection of the diaphragm is resisted by the pull of themagnet pole pieces 75 upon the armature 78, the action of the magnet and armature therefore tending to reinforce the resilience of the diaphragm.-

It will also be apparent that, as the amplitude of vibration of the diaphragm away from the magnet increases the pull of the magnet upon the armature 73 decreases; which we have found to be one feature important for the proper cooperative action of a diaphragm and magnet in telephone transmitters and like instruments. It will be apparent that the action of the magnet in no wise interferes with the variation of resistance of the microphone due to varying compression of the granular carbon; so that this microphone acts to cause the transmisportions of sound waves of different characters and pitch, than is the case with the ordinary telephone transmitter. In particular, and using the same receiver in connection, alternately, with an ordinary transmitter, and with our improved transmitter,

circuit conditions beingotherwise the same,

it has been found that when our transmitter' is used, overtones, not noticeable when the ordinary transmitter is used, are clearly heard, and that articulate speech and other sounds are transmittedmuch more clearly and distinctly. It is also found that there. is a practical suppression of side noise,

so objeetionably prominent when the, ordinary transmitter is used. The use of our magnet and armature, in connection with the ordinary telephone diaphragm, makes On this rod 72 unnecessary the use of the ordinary damping spring, and so permits much freer vibration.

of the diaphragm; while, on the other hand,- the pull of the magnet prevents undue response to very loud noises (the. function of the ordinary damping spring). The transmission of side tone or side noise by the ordinary telephone transmitter, is understood to be due, in large measure at least, to

the fact that in the ordinary transmitter, the damping spring or springs have little or no restraining influence upon the diaphragm when the latter is in or near its normal rest position. Since, according to our invention, the diaphragm is under the stress of a magnet at all times, it is prevented, in very large measure, from responding to sounds not delivered directly into the mouth piece of the transmitter. In practice, the freedom of our transmitter from thetransmission of such. side noises, is very noticeable indeed.

Fig. 3 illustrates the, application of our invention to a somewhat improved form.

of telephone transmitter. In this transmitter the diaphragm, here designated by numeral 65, is supported in an improved manner, and has a better shape. This-improved support for the dialiihragm and form of the diaphragm, is not of our invention, but is illustrated incidentally. The magnets 74 are of thesame construction as shown in Figs. 1 and 2 exceptthat the pole pieces, 7 5, are slightly modified, presenting a contracting space for the play of the correspondingly tapered armature 73.

The improved telephone transmitter above described is readily applicable for the pro duction of'cut phonograph records, the dia phragm of 'thelinstrumnt being actuated mechanically from a master record, instead of by direct voice waves. The ordinary phonograph records on the market are understood to be made by process involving the production of a metal die, from the original wax, record, by electroplatin and from this die the commercial recor s are produced by applying the die, under pres- I sure, to record blanks softened to receive the impress of the die. It isreasonable to suppose that in this electroplating and pressure process of reproduction, much of the delicacy of the original wax record is lost; and that if records be cut mechanically, by instrumen'talities of suflicient delicacy and responsiveness, the delicacy of the original record may be maintained, substantially, in thelcopies produced by cutting In Fig. 4 we illustrate more or less diagrammatically,

apparatus for producing cut records, which 21? shall be true copies of the original or master record. In this figure 76 designates a copying instrument, somewhat similar to the telephone transmitter illustrated in Fig. 3, and comprising adiaphragm 65 suitably supported and provided with a vibrating lever 8 carrying at its lower end a reproitlucing stylus l1 movable over a master record 77. As in Fig. 3, magnets 74: are supported in proximity tothe diaphragm and are provided with pole pieces 75 arranged to infiuence an armature 73 acting upon a microphone 67. It will beclear that the mstrument 76, when actuated by a master record such as 77, Wlll producetelephonic variations of current in a circuit 78. We have n ot illustrated means for moving the master 83. Above the record blank 7 9 are suitable magnets 84. i ncluded in the circuit 78and shown'in this case as having hollow cores 85 within which are mounted, to-move axially, rods86 connected at their Io- Veireiids'tQ reproducer shafts 87, and each carrying a these stylus mountings 88, may

stylus mounting 88. The cutting stylus itself, ,mounted upon the end of each of "the ordinary cutting stylus (in the construction shown a cutting stylus to out lateral indentations), and-we'do'inot deem it necesmounted to move laterally along a slide 89,

the stylus shafts S7 being carried-by such f magnets; and a feed screw 90' driven by suitsary to illustrate such stylus, as it is of well known construction. 'The inagnets 84 are able gearing 91 from the shaft 81, will traverse these magnets and the parts connected thereto. 'lherods 86 carried by armatures 92, are provided with retractile springs 93 acting in opposition to the magnets 84. It will be clear that, as the instrument 76 actuated by master record 77,;pro-

duces telephonic variations in circuit 78,

magnets 84 wili actuate their armatures 92 styli carried by rock shafts 87 'to produce, inrecord blanksj'ii), phonographic'indcntations which are exact v copies of the phonographic indentations of the master record 77, and that'in this way .records mayhe produced, by a cutting op eration, which are exact copies of the original master records. It Wlll further be an .parent that a very large number of record- 'cutting devices may hemciuded 1n the one circuit 78 and therefore'may be actuated. by

a single instrument 76; so that a large num ber of copies of the master record may be produced at one time.

,We have not deemed it necessary to illustrate apparatus to copy records of the hill and valley type; t e necessary modifie tion of the apparatus shown in Fig. -l, to enable it to copy hill and valley records being obvious.

It is well known that by means of magnets operated by a circuit current variations in which are produced by a'tclephone microphone, the sound waves actuating the microphone may be reproduced with very consideral'ile magnification. For this reason ample power may exist, in the magnets 8%, to do the mechanical work of. cutting record blanks 79 of relatively hard material.

In the instrument 76, the diaphragm acts as a more support for the rod 72 carrying the armature 73a support which permits free axial movement of such rod;

for that reason, this diaphragm do need not be a complete disk.

W hat we claim 1s:-

1. A transmitter for recording and variable resistance device and disposed on the same side of the diaphragm as sistance device.

2Q A transmitter for recording and reproducing sound waves comprising in comthe {rebination a diaphragim'a microphone'-ar-- ranged to be actuatedby said diaphragm, and magnetic means tending to pull said diaphragm away from'the microphone and disposed on the same side of the diaphragm as the microphone.

carried thereby, a variable resistance device 3. A transmitter for recording and rc operatively connected to said diaphragm,.

and a magnet mounted upon said diaphragm support tending to pull the diaphragm away from the variable resistance device and disposed on-the same side of the as the resistance device.

d. A i transmitter for recording and reproducingsoundwaves comprising in comhinati on a diaphragm supporfl-a diaphragm carried thereby,.a variable resistance device operatively connected to said diaphragm, a magnet mounted upon said diaphragm support, and an armature operatively connected to said diaphragm, said magnet and armature arranged to pull the diaphragm away from said variable resistance deviceand di posed on the same side of the diaphragm as the resistance device. 1 j r 5. A transmitter for recording and reproducing sound waves comprising in comdiaphrag bination a diaphragmsupport, a diaphragm rep said armature, said armature being disposed on the same side of said diaphragm as said microphone.

6. A transmitter for recording and re- 5 producing sound waves comprising in combination a diaphragm support, a diaphragm carried thereby, a variable resistance device,

' means connecting said diaphragm and variable resistance device, an armature mounted 10 upon such connecting means, a plurality of pairs of magnets, and a pole piece for each v such pair, said pole pieces arranged in 0p- In testimony whereof We have signed scribing Witnesses.

' JAMES G. NOLEN.

ROBERT L. MQELROY.

Witnesses:

H. M. MAR LE; PArm FRANKE.

this specification in the presence of two sub- 

